Assessment of lung pathology after RSV challenge of immunized cotton rats. Panels show scores of lung inflammation in ten cotton rats/group immunized with immunogens indicated at the bottom of each panel and then challenged with RSV at 49 days post immunization. At 4–5 days post challenge, lungs were harvested and tissue sections stained and scored for inflammation as described in "Methods". Differences between FI-RSV immunized animals and all other groups are statistically significant except for scores of perivasculitis, which are not significant. Differences between mock vaccinated, RSV infected, and VLP vaccinated animals in all categories are not statistically significant.